subproject E: "Yield Stability, root development and stress tolerance in winter wheat "
In spite of the documented breeding progress in winter wheat, grain yield has been reported to stagnate on the farm level in Germany and other countries. Several reasons are discussed for the stagnation of yield, e.g. i) the recently observed lower precipitation and rising temperatures during the grain filling period in spring-early summer, ii) the expansion of winter wheat growing into suboptimal sites, iii) changes in crop rotation leading to a higher frequency of wheat cultivation.
However, results from repeated multi-locational exact field trials conducted as part of the collaborative BRIWECS1) project with a set of 220 genetically diverse wheat cultivars, including winter and semi-winter types of different origin and released in different years, shows a significant genetic improvement in grain yield and give no hint that the yield stagnation observed in farmers’ fields would be due to a stagnation of the genetic amelioration of wheat cultivars over the time.
For the selection of improved wheat varieties mainly above ground biomass and associated traits are taken under account, whereas root characteristics remains to be unconsidered. In this regard detailed analysis of root morphology under controlled environmental conditions are carried out with the 220 wheat genotypes, since from other crop plants, e.g. corn, it is known that the root angle is an important trait for the adaption to different abiotic stress conditions. Particularly, the nodal root angle (angle of the nodal roots with the soil surface) will be scored to gain an individual nodal root index (NRI) of each genotype, which will then be used in genome wide association studies to reveal information on the genetic structure of this relevant root trait. In addition, the root morphology data can be used together with the data from the contrasting, multi-locational and multi-year field trials to identify relationships between agronomical performance and root traits.
Alongside, the observed results from the comprehensive field trials demonstrate that the grain yield progress in European winter wheat is strongly influenced by a higher number of kernels per spike in modern cultivars. In this regard detailed phenotyping of different spike morphology traits, e.g. spikelets per spike, spikelet fertility, etc. are undertaken to obtain profound knowledge on the genetic control of this major yield component. Finally, these results will be used for quantitative-genetic studies to determine the genetic basis as well as to describe the breeding history of this fundamental grain yield parameter.
project leader: Prof. Dr. Dr. h.c. Wolfgang Friedt
project assistance: Dr. Benjamin Wittkop